Methods for controlling a display unit or display units are used in a vehicle, in particular in conjunction with navigation systems. In addition to detailed road maps, such navigation systems are able to display a multitude of special destinations (also referred to as points of interest POI). Points of interest are, for instance, elements that are displayed at their geo-positions on the geographic map. They include gas stations, restaurants and landmarks, for example. Furthermore, the position of a friend may be treated as mobile point of interest. Even the purchase of asparagus at the side of the road or a temporary traffic jam may be treated as point of interest. The points of interest are typically placed in categories. The user can choose which category he wishes to have displayed. All points of interest falling into the selected categories will then be shown on the geographic map. However, since this may involve a very high number of points of interest, some navigation systems fade out the special points of interest or display them at reduced size starting with a particular scale.
Such a display of the points of interest has the disadvantage that the user is frequently required to set the desired categories of the points of interest manually. Furthermore, given a multitude of selected categories, a large number of points of interest is also shown simultaneously, so that the user loses track of things rapidly. All points of interest located in the visible region of the map will be displayed, without taking the type of the points of interest into consideration.
German Published Patent Application No. 199 41 966 describes a method and a device for the display of warning messages. A display unit of a navigation system displays a digital road map on which points of interest have been marked. Furthermore, warning messages are displayed on the digital road map at their geographic positions, using pictograms. Due to the local distribution of the warning messages, it is very easy for the vehicle driver to judge the relevance of the individual warning messages for his or her own route. A disadvantage of the method is that a great many points of interest may be shown simultaneously, so that the display becomes cluttered.
A display device for vehicles for displaying the range is described in German Published Patent Application No. 197 41 316. Using a navigation system, the distance of the instantaneous driving location to the desired destination is calculated. Furthermore, it is calculated whether the available energy quantity is sufficient to reach the destination without refueling. If it turns out that the destination cannot be reached without refueling, then a message about the gas stations available via a specific detour from the direct route to the destination will be provided. These gas stations are displayed on a display indicating the distance, independently of the display of the navigation system.
An information display device for vehicles is described in German Published Patent Application No. 696 13 653. In this display device, the importance of information is evaluated as a function of a determined driving state, and the information is displayed according to the degree of importance.
Disadvantageous in this information display device is that it is difficult for the user to understand the information easily and intuitively.